This invention relates to impurity detectors. More particularly, this invention relates to impurity detectors using scattered electromagnetic radiation.
Electromagnetic radiation incident on a sample of bulk material undergoes angular scattering due to reflection, interference, and refraction. The magnitude of the scattered radiation depends on the wavelength of the incident radiation, the bulk dielectric constant of the material, and the shape and homogeneity of the sample. Prior to this invention, simple absorption of radiation and scattered cross polarized radiation have been used to analyze samples of bulk material. See, for example, Pullman U.S. Pat. No. 3,360,721, Prine U.S. Pat. No. 3,549,986, and Jawor U.S. Pat. No. 3,783,373. It has been found that parallel polarized scattered radiation is particularly suitable for impurity detection in bulk materials having a predetermined size and shape.